Restaurants and food service providers must have quick access to both hot and cold foods to assemble sandwiches and meals for delivery to customers. Food is likely to be prepared in batches and stored in a food holding appliance near the point of assembly. The food must be held in a food safe environment that inhibits the growth of bacteria and also preserves the quality of the food throughout the holding time. It is important that all food components of a meal be close to the point of assembly to increase the efficiency and speed of the preparation staff. As food service restaurants increase their menu offerings the number of unique food components increases, creating demand for more flexible hot and cold food holding capacity that can be configured to give each food product a unique thermal treatment. There is a need for a flexible food holing appliance that can hold both hot and cold foods without requiring too much counter top space in the preparation area. Counter top space is highly valued in commercial restaurants and it is important to have the flexibility to hold both hot and cold food products as close to the point of use as possible. This requires the use of the vertical space above the counter top which is usually not utilized as efficiently as possible. The ability to utilize the vertical space efficiently requires a combination of hot and cold food storage that is not available in existing food holding appliances. The flexibility to change a food holding space from hot to cold will further enhance the efficiency and utility of a food holding appliance allowing the food service provider to change their menu offerings quickly using one food holding appliance instead of several different appliances.
Food holding appliances in use today usually arrange food pans in an array distributed across a planar surface. Hot food holding is accomplished by filling a rectangular container with hot water and suspending the food pans over the hot water, U.S. Pat. No. 4,274,391 shows this design. Cold food holding is very similar with food holding pans suspended over a rectangular box or channel that is wrapped with refrigeration coils or with forced cold air around the bottom, sides, and over the top surface of the food pans, U.S. Pat. Nos. 6,722,150 and 5,282,367. The top surface of the food pans are arranged in an array distributed over a flat surface with the top of the food pan parallel or slightly below the top surface. These food holing appliances require considerable counter top space with food holding pans arranged in horizontal rows distributed in an array across the surface. Both of these food holding appliances are typically used in salad bars and hot food serving lines for food buffet arrangements. They are also commonly used in the food preparation kitchen for holding hot and cold food prior to assembly of meals.
Hot and cold food holding cabinets circulate air around the pans and over the surface of the food. U.S. Pat. Nos. 4,250,955 and 6,670,585 illustrate this type of appliance. The food pans are contained within an enclosed cabinet and a means to control the humidity and temperature of the air may be provided. Access to the food is provided by a door that is opened and closed. Some types of holding cabinets can be changed from hot to cold within the same appliance by circulating hot or cold air through the cabinet. All of the food pans contained within the cabinet share the same circulated hot or cold air. Multiple food pans are supported by shelves built in to the interior of the cabinet.
There are other hot food holding appliances that arrange the food holding pans in an array of compartments that can be vertically and horizontally distributed. U.S. Pat. Nos. 5,947,012 and 6,541,739 illustrate this type of holding appliance. These units typically eliminate the use of water for humidification, using conductive or radiant heat to keep the food at an acceptable holding temperature. In some units the temperature of each hot holding compartment can be individually controlled. In some units the compartment is sized to fit the food pan, while others use a large rectangular compartment that can hold one or more food pans with radiant heat supplied from the top and bottom surfaces.
Hot and cold food holding appliances that arrange the food pans in an array along a planar surface suffer from many limitations. They use a large amount of valuable counter top space, making it difficult to hold multiple food products close to the point of assembly causing the food preparation worker to move from the assembly station to another location to access each food item. This is an inefficient use of labor that would not be necessary if multiple food products were held in a vertical array in front of the point of assembly. Workers often remove empty pans from steam heated holding units allowing the release of steam vapor which wastes energy. The water must be replaced and heated each day before food pans can be placed in to the holding unit and emptied every night to sanitized the equipment of bacteria laden food particles that have accumulated. The refrigerated units extract heat energy from the food pans by encircling them with cold walls or forcing cold air around the food pan bottom, sides, and top. It is very difficult to maintain consistent temperatures and quality. Cold air is dry and humidity can not be added because it will cause a disabling build up of frost on the evaporator coils. Dry, cold air will dry out food products and degrade the quality. Both hot and cold holding units rely on the operator to replace the food pan cover after dispensing food to keep the food quality and temperature in the range of acceptability since the exposed top surface will be affected by the restaurant kitchen environment. Due to the difficulties listed above, it is very difficult to hold hot and cold food products close to the point of assembly while maintaining acceptable quality.
Food holding cabinets are able to vertically integrate food holding space but suffer from a number of problems that make them inefficient and difficult to use. The food holding compartment that forms the interior of the cabinet gives each pan in the compartment the same thermal treatment by circulating hot, humidified, or cold dry air throughout the compartment. The temperature is not even, causing hot or cold spots. Every time the cabinet door is opened, the entire conditioned air content of the cabinet must be re-generated. This is a waste of energy when the cabinet contents must be repeatedly accessed to assemble food items for serving. All of the foods will share the same air within the cabinet so the transfer of flavor from one food item to another can only be stopped by adding a cover to each food pan. This cover must be removed and replaced each time the food pan is accessed for serving. Since the cabinet environment gives all of the food pans the same thermal treatment, separate cabinet compartments must be used for hot and cold food products. Holding cabinets require expensive fans, motors, and humidity generation systems to function making them expensive to purchase, maintain, and repair.
Food holding appliances that arrange food holding pans in an array of compartments eliminate some of the problems listed above but can not be used to hold a combination of hot and cold foods in one appliance. Cold food must be held in one of the other food holding units described above.